West Nile Virus: Background and Ecology First isolated in West Nile district, Uganda, 1937 Commonly found in humans and birds and other vertebrates in Africa, Eastern Europe, West Asia, and the Middle East, but has not previously been documented in the Western Hemisphere Basic transmission cycle involves mosquitoes feeding on birds infected with the West Nile virus Infected mosquitoes then transmit West Nile virus to humans and animals when taking a blood meal

West Nile Virus Outbreaks  Israel – , 1957, 2000  France – 1962, 2000  South Africa –1974  Romania –1996  Italy – 1997  Russia – 1999  U. S. A. –

Humans Spread of West Nile Virus in the U.S. 7/30/02

WNV Case-Patient Demographics & Mortality United States, Number8366 Age (yr) median median6568 range range Males54%65% CFR11%14%

Date of Symptom Onset, West Nile Virus United States, /78/49/1 9/29 10/2711/2412/23 Week ending Number of cases

Clinical Epidemiology  Incubation period days  20% develop “West Nile fever”  1 in 150 develop meningoencephalitis –Advanced age primary risk factor for severe neurological disease and death

West Nile Fever: Classic Clinical Description Mild flu-like illness of sudden onset Duration days Fever, swollen lymph nodes, headache, abdominal pain, vomiting, rash, conjunctivitis, eye pain, anorexia Symptoms of West Nile fever in contemporary outbreaks not fully studied

Symptoms of Hospitalized Patients with West Nile Virus 2% Swollen Lymph Nodes 19%Rash 27%Diarrhea 46% Change in mental status 47%Headache 51%Vomiting 53%Nausea 56%Weakness 90%Fever

Risk of West Nile Virus Transmission Through Blood Transfusion Concern: most WNV infections have no or only mild symptoms, and transient viremia occurs after infection Concern: most WNV infections have no or only mild symptoms, and transient viremia occurs after infection Transfusion-transmission of WNV or other related flaviviruses not reported, but plausible Transfusion-transmission of WNV or other related flaviviruses not reported, but plausible Mathematical modeling: estimated risk of transfusion- transmission was 2 in 10,000 during NYC outbreak (Transfusion, Aug 2002) Mathematical modeling: estimated risk of transfusion- transmission was 2 in 10,000 during NYC outbreak (Transfusion, Aug 2002) WNV should be considered in persons who develop unexplained fever, meningitis, or encephalitis after transfusion WNV should be considered in persons who develop unexplained fever, meningitis, or encephalitis after transfusion

West Nile Virus

Mosquitoes  Usually Culex Genus  Pipiens or Restuans species are most common carriers in this area  Only the females bite  Males feed on nectar  Normally only ¼ “ long  “Huge” mosquitoes are really crane flies

Mosquito Lifecycle  Egg raft  Up to 300 eggs  Hatch within 3 days  Larvae  Wigglers  Pupae  Tumblers  Become adults within a few days  Adult  Males Live one week  Females live one month  Flight range up to ½ mile

West Nile Virus Transmission Cycle  Mosquito infects bird while taking a “blood meal”  Other mosquitoes pick up the virus from the infected bird  Humans and animals (horses) get the virus from infected mosquitoes  ONLY MOSQUITOES CAN SPREAD WEST NILE VIRUS

West Nile Virus Transmission Cycle

Dead Birds  Virus found in over 100 species of birds  Predominant species: –Hawks –Owls –Crows –Blue jays  Call PA HEALTH  Only five birds are tested weekly

Hawks  Length: 18 inches Wingspan: 48 inches  Short, dark, hooked beak  Large, broad-winged, broad-tailed hawk  Immatures have notably narrower wings and tail, and appear slimmer  Dark patagial mark on underwing, present on all ages and races, is unique

Owls  Length: 8 inches Wingspan: 22 inches  Small, nocturnal, predatory bird  Large, rounded head with ear tufts  Yellow eyes  Dense streaking on underparts with finer barring  Some birds have rusty plumage, others dark gray

Bluejays  Length: 10 inches  Black sturdy bill  Blue crest and upperparts  Black eyeline and breastband  Grayish-white throat and underparts  Bright blue wings with black bars and white patches  Long blue tail with black bars and white corners  Dark legs

Crows  Length: 17 inches  Entirely black plumage  Squared-off tail  Very common in urban and agricultural areas

Washington County WNV Program  Surveillance of known problem areas  Surveillance of citizen complaints  Samples sent to PA DOH for analysis  Positive areas are treated  Heavily infested areas are treated  Purpose is not to eradicate the mosquito population

Dead Bird Reports Dead Bird Testing Live Bird Testing Mosquito Testing Equine Cases Human Cases West Nile Virus Surveillance West Nile Virus Surveillance

Gravid Trap  Lactalbumin water is an attractant  Draws mosquitoes into trap from the bottom  Easier to use  More effective than light traps

Gravid Trap

Light Trap  Carbon dioxide and light used as attractants  Color  Collection bin hangs from the bottom

West Nile Virus – Human Cases Mosquito Control Personal Protection PREVENTION

 Avoid black and white  Wear long sleeves  Wear long pants Personal Protection Clothing

Home needs to be “Bug Tight” Stay indoors at dusk and dawn Use insecticides at dusk and dawn Use white incandescent lights Vitamin “B”, “Bug Zappers”, and “ultrasonic” devices are ineffective Personal Protection Avoidance

Repellant  Deet  Bite Blocker  Avon Skin So Soft Read and understand label directions Apply lightly to skin and clothing Personal Protection

Mosquitoes Can Kill

Mosquito Control

Habitat Elimination Adulticiding Larviciding

Adulticiding  Malathion  Organophosphate  Applied in “Ultra Low Volume”  Can be toxic to humans  Originally, only done for positive test areas  Will be done for heavy infestations

Larviciding PPPPreferred method of control MMMMicrobial – BTI, CG, and WDG NNNNaturally occurring bacteria NNNNon-toxic to humans and animals MMMMethoprene GGGGrowth regulating hormone AAAApplied to ditches, ponds, marshes TTTTemephos OOOOrganophosphate pesticide CCCCan pose a human health hazard MMMMonomolecular films & Oils CCCCauses larvae and pupae to drown PPPPoses little risk to humans, wildlife, and the environment

Natural Predators  Purple Martins  Bats  Mosquito fish  Other breeds of mosquitoes  Mosquitoes are not the meal of choice

Habitat  Catch basins  Clogged bodies of water  Construction depressions  Flooded Flower pots  Public dumps  Birdbaths  Unfiltered swimming pools  Cemetery urns  Clogged rain gutters  Boats  Rain barrels  Hoof prints  Swamps  Tree holes  Tin cans  Tires

Control Breeding Sites  Turn over pools and wheel barrows  Dispose of things that can hold water i.e. tires, tin cans, broken toys, etc.  Drill holes in permanent containers  Clean clogged roof gutters  Empty accumulated water from boats  Keep outdoor water fresh  Landscape your property  Keep grass cut and weeds pulled

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